CN118087877A - Post-tensioning method prestress construction method and prestress reinforced concrete member - Google Patents

Abstract

The present disclosure provides a post-tensioning method prestressed construction method and a prestressed reinforced concrete member, comprising: s1, asphalt is coated on the periphery of a prestressed reinforcement and cured; s2, casting concrete on the prestressed reinforcement to form a common concrete member; and S3, electrifying and heating the prestressed reinforcement to soften the asphalt and elongate the prestressed reinforcement. Through the technical scheme, the construction method utilizes the solid state characteristic of asphalt to form a pore canal inside a concrete structure when concrete is poured at normal temperature, and then utilizes the temperature rise of the prestressed reinforcement to soften the asphalt when electric heating tensioning is carried out, so that the prestressed reinforcement can freely stretch in the pore canal, the problem caused by the pre-buried corrugated pipe in the traditional post-tensioning construction is avoided, and the forming quality of the prestressed concrete member is improved.

Description

Post-tensioning method prestress construction method and prestress reinforced concrete member

Technical Field

The disclosure relates to the technical field of prestressed concrete construction, in particular to a post-tensioning method prestressed construction method and a prestressed reinforced concrete member.

Background

Compared with the common reinforced concrete structure, the prestressed reinforced concrete structure has the advantages of light dead weight, high rigidity, good durability, high cracking resistance and the like, and is widely applied to building structures such as large-span bridges, large roof boards, hollow floors and the like.

The construction of the prestressed reinforced concrete structure is divided into a pretensioning method and a post-tensioning method, wherein the post-tensioning method refers to a construction method of pouring concrete first, and tensioning prestressed steel after the strength of the concrete structure reaches more than 75% of the design strength to form the prestressed concrete member. The conventional method is that before concrete is poured, a corrugated pipe is pre-buried in a steel bar framework, after the strength of a member reaches the standard, prestressed steel bars are penetrated into reserved pore channels, prestressing is applied, and then the pore channels are grouted and maintained. The traditional post-tensioning method construction has some objective defects: because of the existence of the reserved pipeline, concrete near the pipeline is not easy to compact during pouring; the pre-buried corrugated pipe is easy to be broken by the collision of the vibrating rod when concrete is poured, so that the pore-forming is influenced; the prestress rib is deviated, worn and the like in the perforation process; after the prestressed reinforcement is stretched, if the grouting is not performed in time under the high stress state, rust and the like are easy to generate.

Disclosure of Invention

One technical problem to be solved by the present disclosure is: how to solve the problem of the traditional post-tensioning method prestressed reinforced concrete member caused by the pre-buried corrugated pipe.

In order to solve the above technical problems, an embodiment of the present disclosure provides a post-tensioning method prestress construction method, including: s1, asphalt is coated on the periphery of a prestressed reinforcement and cured; s2, casting concrete on the prestressed reinforcement to form a common concrete member; and S3, electrifying and heating the prestressed reinforcement to soften the asphalt and elongate the prestressed reinforcement.

In some embodiments, further comprising: and S4, cutting off the power supply and anchoring after the prestressed reinforcement is stretched to a preset stretching amount to form the prestressed concrete member.

In some embodiments, in S1, external threads are respectively machined at two ends of the prestressed reinforcement, and nuts are screwed at two ends of the prestressed reinforcement; in S4, nuts are applied to both ends of the prestressed concrete member to transmit the prestress of the prestressed reinforcement.

In some embodiments, in S1, pre-embedded plates are respectively sleeved at two ends of the pre-stressed steel bar; in S2, after the concrete is poured, the outer surface of the embedded plate is coplanar with the end surface of the common concrete member.

In some embodiments, in S2, the two ends of the common concrete member are divided into an anchored end and a tensioned end; and in S3, before the power-on heating, fixing the prestressed reinforcement at one side of the anchoring end relative to the embedded plate.

In some embodiments, in S4, when the prestressed reinforcement is elongated by energizing, a backing plate is provided between the nut on the tension end side and the pre-buried plate.

In some embodiments, in S3, the pre-stressing rebar is subjected to a trial tension prior to energizing.

In some embodiments, prior to energizing the prestressed reinforcement, the plain concrete member is cured until the concrete strength reaches more than 75% of the design strength.

In some embodiments, in S2, a plurality of symmetrical pairs of pre-stressed steel bars are disposed within the common concrete member; and S3, symmetrically tensioning the symmetrical pairs of prestressed reinforcement respectively.

The present disclosure also provides a prestressed reinforced concrete member, and the manufacturing process of the prestressed reinforced concrete member adopts the construction method of the prestressed reinforced concrete.

Through the technical scheme, the post-tensioning method pre-stressing construction method and the pre-stressing reinforced concrete member provided by the disclosure form a pore channel in the concrete structure by utilizing the solid characteristic of asphalt when concrete is poured at normal temperature, and soften the asphalt by increasing the temperature of the pre-stressing reinforcing steel bar when electric heating tensioning is performed, so that the pre-stressing reinforcing steel bar can be freely stretched in the pore channel, the problem of pre-embedding corrugated pipes in the traditional post-tensioning method construction is avoided, and the forming quality of the pre-stressing reinforced concrete member is improved.

Drawings

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.

FIG. 1 is a schematic plan view of the end of S1 disclosed in the embodiments of the present disclosure;

FIG. 2 is a schematic plan view of the end of S2 of the presently disclosed embodiments;

FIG. 3 is a schematic plan view of the end of S3 of the presently disclosed embodiments;

FIG. 4 is a schematic plan view of the end of S4 of the presently disclosed embodiments;

Fig. 5 is a schematic plan view of a prestressed reinforcement end screw thread as disclosed in an embodiment of the present disclosure;

Fig. 6 is a plan and cross-sectional comparison view of the pre-stressed steel bar before and after asphalt coating in S1 disclosed in the example of the present disclosure;

FIG. 7 is a schematic plan view of a tensioning end at the end of S4 as disclosed in an embodiment of the present disclosure;

fig. 8 is a schematic plan view of an anchor end at the end of S4 as disclosed in an embodiment of the present disclosure.

Reference numerals illustrate:

1. Prestress steel bars; 101. a thread; 102. a nut; 2. asphalt; 3. a common concrete member; 31. an anchor end; 32. stretching the end; 4. embedding a plate; 5. a prestressed concrete member; 6. a backing plate; 7. and electrifying the lead.

Detailed Description

Embodiments of the present disclosure are described in further detail below with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the disclosure and not to limit the scope of the disclosure, which may be embodied in many different forms and not limited to the specific embodiments disclosed herein, but rather to include all technical solutions falling within the scope of the claims.

The present disclosure provides these embodiments in order to make the present disclosure thorough and complete, and fully convey the scope of the disclosure to those skilled in the art. It should be noted that: the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments should be construed as exemplary only and not limiting unless otherwise specifically stated.

In the description of the present disclosure, unless otherwise indicated, the meaning of "plurality" is greater than or equal to two; the terms "upper," "lower," "left," "right," "inner," "outer," and the like indicate an orientation or positional relationship merely for convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the devices or elements being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the present disclosure. When the absolute position of the object to be described is changed, the relative positional relationship may be changed accordingly.

Furthermore, the use of the terms first, second, and the like in this disclosure do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The "vertical" is not strictly vertical but is within the allowable error range. "parallel" is not strictly parallel but is within the tolerance of the error. The word "comprising" or "comprises" and the like means that elements preceding the word encompass the elements recited after the word, and not exclude the possibility of also encompassing other elements.

It should also be noted that, in the description of the present disclosure, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the terms in the present disclosure may be understood as appropriate by those of ordinary skill in the art. When a particular device is described as being located between a first device and a second device, there may or may not be an intervening device between the particular device and either the first device or the second device.

All terms used in the present disclosure have the same meaning as understood by one of ordinary skill in the art to which the present disclosure pertains, unless specifically defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods, and apparatus should be considered part of the specification.

As shown in fig. 1 to 4 and 6, the present disclosure provides a post-tensioning method pre-stressing construction method, including S1, coating asphalt 2 on the outer circumference of a pre-stressing reinforcement 1 and curing it; s2, casting concrete on the prestressed reinforcement 1 to form a common concrete member 3; and S3, electrifying and heating the prestressed reinforcement 1 to soften the asphalt 2 and elongate the prestressed reinforcement 1.

Specifically, in S1, asphalt 2 is heated to a liquid state and wrapped on the surface of prestressed reinforcement 1, for facilitating later adjustment, a certain anchoring length should be reserved at both ends of prestressed reinforcement 1, then standing and cooling are performed to solidify asphalt 2, then the surface of prestressed reinforcement 1 is inspected, asphalt 2 is coated on the exposed part until the surface of prestressed reinforcement 1 is completely wrapped by asphalt 2, and the purpose of this step is to prevent the exposed surface of prestressed reinforcement 1 from being bonded with concrete when concrete is poured, thereby influencing the elongation of prestressed reinforcement 1 when the subsequent stretching is performed;

In S2, binding the prestressed reinforcement 1 to a design position on a reinforcement cage formed by common reinforcement, however, in other embodiments, other fixing modes such as welding may be adopted, which are not limited in this disclosure, and after the prestressed reinforcement 1 is fixed, concrete is poured to form a common concrete member 3 without prestress, and because the concrete is poured at normal temperature, the asphalt 2 is not softened in the pouring process to affect the covering effect;

In S3, an electric current is applied to the prestressed reinforcement 1, and the prestressed reinforcement 1 is heated and expanded by using a thermal effect of the electric current, and meanwhile asphalt 2 covering the periphery of the prestressed reinforcement 1 is heated and softened to generate fluidity, so as to allow the prestressed reinforcement 1 to freely stretch, thereby realizing tensioning of the prestressed reinforcement 1.

As shown in fig. 1 to 4, in some embodiments, further includes: and S4, after the prestressed reinforcement 1 is stretched to a preset stretching amount, power is cut off and anchored to form the prestressed concrete member 5.

Specifically, in S4, the prestressed reinforcement 1 expands due to the thermal effect of the current, when the elongation of the prestressed reinforcement 1 reaches the preset elongation, both ends of the prestressed reinforcement 1 are anchored at both ends of the ordinary concrete member 3 while the power is turned off, and as the temperature gradually decreases, the prestressed reinforcement 1 is cooled and retracted to generate a contraction force acting on both ends of the ordinary concrete member 3, equivalently, prestressing both ends of the ordinary concrete member 3 to convert the ordinary concrete member 3 into the prestressed concrete member 5.

As shown in fig. 1 and 5, in some embodiments, in S1, external threads 101 are respectively formed at both ends of the prestressed reinforcement 1, and nuts 102 are screwed at both ends of the prestressed reinforcement 1; in S4, nuts 102 act on both ends of the prestressed concrete member 5 to transmit the prestress of the prestressed reinforcement 1. Specifically, the nuts 102 may be moved back and forth on the prestressed reinforcement 1 by means of the threads 101, and in S4, both ends of the prestressed reinforcement 1 are fixed to the ordinary concrete member 3 by rotating the nuts 102 to apply prestress to the ordinary concrete member 3 to form the prestressed concrete member 5.

As shown in fig. 1 to 4, in some embodiments, in S1, pre-buried plates 4 are respectively sleeved at two ends of the prestressed reinforcement 1; s2, after concrete is poured, the outer surface of the embedded plate 4 is coplanar with the end face of the common concrete member 3.

Specifically, the embedded plates 4 are arranged at two ends of the common concrete member 3, so that the nuts 102 can act on the embedded plates 4 to distribute the prestress, if the nuts 102 directly act on the end face of the common concrete member 3, the concentrated prestress can squeeze and crush the concrete on the end face, a part of the prestress steel bar 1 is retracted to weaken the prestress, and the end face concrete crushing can expose part of the steel bar framework to the air to cause corrosion of the steel bar framework and influence the forming quality of the prestress concrete member 5;

Meanwhile, the prestressed reinforcement 1 passes through the pre-buried plate 4, and the prestressed reinforcement 1 can move along the perforation direction relative to the pre-buried plate 4, so that when the prestressed reinforcement 1 is heated subsequently and the prestressed reinforcement 1 stretches, the prestressed reinforcement 1 and the pre-buried plate 4 can move relatively, and the prestressed reinforcement 1 and the pre-buried plate are not fixedly arranged together. However, the embedded plate 4 needs to be mutually fixed with a steel reinforcement framework formed by common steel bars, so that the position of the embedded part 4 in the common concrete member 3 can be determined, the outer surface of the embedded part 4 is coplanar with the end surface of the common concrete member 3 after concrete is poured, so that the best forming effect is achieved, if the outer surface of the embedded part 4 is positioned in the end surface of the common concrete member 3, part of concrete exists between the nut 102 and the embedded part 4, the nut 102 is pressed on the concrete, so that the concrete is crushed to expose the steel reinforcement framework to rust, and meanwhile, part of the prestressed steel bars 1 is retracted, so that the size of prestress is weakened; if the outer surface of the embedded part 4 is outside the end surface of the common concrete member 3, the contact area between the embedded part 4 and air is increased, and the embedded part 4 is usually made of metal, so that corrosion of the embedded part is accelerated.

As shown in fig. 2 to 3, in some embodiments, in S2, both ends of the general concrete member 3 are divided into an anchor end 31 and a tension end 32; in S3, the prestressed reinforcement 1 at the side of the anchor end 31 is fixed to the pre-buried plate 4 before the electric heating.

In actual construction, if mechanical tensioning is adopted, when the prestressed reinforcement 1 distributed in a curve or the prestressed reinforcement 1 is larger than a certain length, two ends of tensioning are sometimes adopted in consideration of friction loss, and then the concrete structure does not need to distinguish the anchored end 31 from the tensioned end 32, but because the electrothermal tensioning adopted by the present disclosure has the characteristic of no friction loss, the prestressed reinforcement 1 expands due to the thermal effect of current, the elongation of the prestressed reinforcement 1 gradually increases along with the time change of the current passing through the prestressed reinforcement 1, if the elongation is distributed at two ends, the total elongation is not easy to monitor, so the two ends of the common concrete member 3 are distinguished into the anchored end 31 and the tensioned end 31, and the elongation is completely controlled at the tensioned end 31 in a one-end tensioning mode, so that the change of the elongation is convenient to monitor. Since the pre-buried plate 4 is fixed on the end face of the common concrete structure 3, the pre-stressed steel bar 1 on the side of the anchoring end 31 can not move relative to the anchoring end 31 along with the thermal effect of current by fixing the nut 102 on the side of the anchoring end 31 on the pre-buried plate 4, and in other embodiments, a weight can be used to prop against the pre-stressed steel bar 1 on the side of the anchoring end 31. The stretching amount of the prestressed reinforcement 1 is concentrated on one side of the stretching end 32, so that the power supply can be cut off in time after the stretching amount of the prestressed reinforcement 1 reaches a design value, and the waste of electric energy caused by overstretching is avoided.

As shown in fig. 3 and 4, in some embodiments, when the prestressed reinforcement 1 is elongated by energizing S4, a spacer 6 is provided between the nut 102 on the side of the tension end 32 and the pre-buried plate 4. The thickness of the backing plate 6 can be equal to the elongation of the prestressed reinforcement 1, when the prestressed reinforcement 1 is stretched to the designed length by electric heating, the nut 102 on one side of the stretching end 32 is not fixedly connected with the embedded part 4, and meanwhile, a certain amount of elongation is generated by the prestressed reinforcement 1, so that a certain gap exists between the nut 102 on one side of the stretching end 32 and the embedded part 4, the backing plate 6 is placed in the gap, the power supply is cut off, and the heat effect of losing current of the prestressed reinforcement 1 can begin to retract. Then, when the nuts 102 are tightly attached to the surface of the backing plate 6 by waiting for the retraction of the prestressed reinforcement 1, the anchoring of the prestressed reinforcement 1 at the tensioning end 32 can be completed, the elongation of the prestressed reinforcement 1 can be precisely controlled by controlling the thickness of the backing plate 6, and the defect that the electrothermal tensioning is not easy to control the elongation is overcome. Of course, the backing plate 6 may also be of a different thickness than the elongation so that the magnitude of the prestress may be adjusted by the nut 102.

As shown in fig. 7, the pad 6 may be a U-shaped pad, so that when the pad 6 is placed, the U-shaped opening may be downward, so that the pad 6 may be placed on the prestressed reinforcement 1 through the downward opening, so that the pad 6 may be placed, however, in other embodiments, the pad 6 may be other shapes, which is not limited in the disclosure.

In some embodiments, in S3, the pre-stressing rebar 1 is subjected to a trial tension prior to being energized. The trial tensioning is performed prior to the formal tensioning. On the one hand, the method can check whether the circuit system has faults or not, and on the other hand, the method can test the tension to measure the voltage and the current passing through the prestressed reinforcement 1 so as to determine the wiring mode adopted in the formal tension to control the elongation more accurately. Specifically, the electrothermal tensioning generally applies current to the prestressed reinforcement 1 in a low-voltage and high-current mode, and when the current and the voltage meet the requirements or only the current meets the requirements and the voltage is larger, the prestressed reinforcements 1 are arranged in series, so that the same current passing through each prestressed reinforcement 1 can be ensured, the same elongation is generated in the same time, and the control is convenient; when the voltage can only meet the requirement and the current is large, the prestressed reinforcement 1 is arranged in parallel, so that each prestressed reinforcement 1 can obtain sufficient voltage to facilitate the tensioning operation.

In some embodiments, prior to energizing the pre-stressing rebar 1, the plain concrete member 3 is cured until the concrete strength reaches more than 75% of the design strength. This makes it possible to provide the ordinary concrete member 3 with a certain strength when the prestress is applied to both ends of the concrete, and to avoid damage caused by the prestress. Of course, if the designer has additional requirements for the strength of the ordinary concrete member 3 at this stage, the present disclosure should not be limited according to the designer's requirements.

In some embodiments, in S2, pairs of symmetrical pre-stressing tendons 1 are provided inside a common concrete member 3; in S3, a plurality of symmetrical pairs of prestressed reinforcement 1 are symmetrically tensioned, respectively. The advantage of prestressing is that the excellent compressive property of concrete and the excellent tensile property of steel bars are utilized to improve the stress performance of the integral member. In actual construction, the prestressed reinforcement 1 is generally arranged at the bottom of the concrete beam, so that the bottom of the prestressed concrete beam 5 generates prestress, the top of the prestressed concrete beam 5 generates pretension, after the prestressed concrete beam 5 finishes construction, other types of loads enable the bottom of the prestressed concrete beam 5 to generate tension, and the top of the prestressed concrete beam 5 generates pressure, so that the pre-applied stress can be counteracted with the stress generated by the subsequent load, and the number of cracks on the surface of the prestressed concrete beam 5 is reduced. The symmetrical stretching of the prestressed reinforcement 1 can enable the prestressed concrete beam 5 to generate pretension force only at the top, and the lateral tensile forces of the prestressed reinforcement 1 acting on the prestressed concrete beam 5 are mutually offset due to the symmetrical stretching, so that the prestressed concrete is prevented from being subjected to pretension force as much as possible. Of course, if the concrete beam is of a profiled cross section, the prestressed reinforcement 1 should be tensioned symmetrically as well, in order to avoid subjecting the concrete element to excessive pretension.

The present disclosure also provides a prestressed reinforced concrete member manufactured by the construction method of prestressed reinforced concrete described above. The construction method is different from the existing post-tensioning construction process of the pre-buried corrugated pipe, the phenomenon that concrete around the pre-stressed reinforced concrete 1 is not compact is greatly reduced, the problem of pore-forming quality defect does not exist, and because the electric heating tensioning is adopted, the phenomena of deviation, abrasion and the like of the pre-stressed reinforced concrete 1 in the perforation process are avoided, meanwhile, the pre-stressed reinforced concrete 1 is fully wrapped by asphalt 2, the possibility of being corroded is greatly reduced, and the forming quality of the pre-stressed reinforced concrete is better due to the differences.

Thus, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concepts of the present disclosure, some details known in the art are not described. How to implement the solutions disclosed herein will be fully apparent to those skilled in the art from the above description.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It will be understood by those skilled in the art that the foregoing embodiments may be modified and equivalents substituted for elements thereof without departing from the scope and spirit of the disclosure. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict.

Claims (10)

1. The post-tensioning method prestress construction method is characterized by comprising the following steps of:

S1, coating asphalt (2) on the periphery of a prestressed reinforcement (1) and solidifying the asphalt;

S2, casting concrete on the prestressed reinforcement (1) to form a common concrete member (3);

s3, electrifying and heating the prestressed reinforcement (1) to soften the asphalt (2) and stretch the prestressed reinforcement (1).

2. The post-tensioning method prestressing construction method according to claim 1, further comprising: and S4, after the prestressed reinforcement (1) is stretched to a preset stretching amount, power is cut off and anchored to form the prestressed concrete member (5).

3. The post-tensioning method prestress construction method according to claim 2, wherein in S1, external threads (101) are respectively machined at both ends of the prestress steel bar (1), and nuts (102) are screwed at both ends of the prestress steel bar (1);

In S4, the nuts (102) act on both ends of the prestressed concrete member (5) to transmit the prestress of the prestressed reinforcement (1).

4. The post-tensioning method prestress construction method according to claim 3, wherein in S1, pre-buried plates (4) are respectively sleeved at two ends of the prestress steel bar (1); in S2, after concrete is poured, the outer surface of the embedded plate (4) is coplanar with the end face of the common concrete member (3).

5. The post-tensioning method pre-stressing construction method according to claim 4, characterized in that in S2, the two ends of the ordinary concrete member (3) are divided into an anchoring end (31) and a tensioning end (32); in S3, before the electric heating, the prestressed reinforcement (1) at one side of the anchoring end (31) is fixed relative to the embedded plate (4).

6. The post-tensioning method prestressing construction method according to claim 5, wherein a backing plate (6) is provided between the nut (102) on the tensioning end (32) side and the pre-buried plate (4) when the prestressing steel bar (1) is elongated by energizing in S4.

7. The post-tensioning method prestress construction method according to claim 1, characterized in that in S3, the prestressing steel bar (1) is subjected to trial tensioning before being energized.

8. The post-tensioning method pre-stressing construction method according to claim 1, characterized in that the ordinary concrete member (3) is cured until the concrete strength reaches more than 75% of the design strength before the pre-stressing steel bar (1) is energized.

9. Post-tensioning method pre-stressing construction method according to claim 1, characterized in that in S2, pairs of symmetrical pre-stressing tendons (1) are arranged in the ordinary concrete member (3);

in S3, symmetrically stretching the symmetrical pairs of prestressed reinforcements (1) respectively.

10. A prestressed reinforced concrete member, characterized by being produced by the post-tensioning method prestressing construction method according to any one of claims 1 to 9.